Vacuum apparatus and method for managing residual limb volume in an artificial limb

ABSTRACT

A hypobarically-controlled artificial limb for amputees includes a single socket with a volume and shape to receive a substantial portion of the residual limb. A liner with a volume less than the residual limb is donned over the residual limb, with the liner tensioned into a total contact relationship with the residual limb. A sealed cavity is formed between the socket and the liner. A vacuum source is connected to the socket cavity thereby drawing the residual limb and liner into firm and total contact with the socket. To compensate for some air leakage past the seal, there is a mechanism to maintain the vacuum in the cavity.

This application is a continuation-in-part of U.S. patent applicationSer. No. 09/492,406, filed Jan. 27, 2000, which is acontinuation-in-part of U.S. patent application Ser. No. 09/325,297,filed Jun. 3, 1999, now abandoned, and a continuation-in-part of U.S.patent application Ser. No. 09/534,274, filed Mar. 23, 2000, which isalso a continuation-i-part of U.S. patent application Ser. No.09/325,297, filed Jun. 3, 1999, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to prosthetic devices and moreparticularly to a hypobarically-controlled artificial limb for amputeesand to a method for preventing loss of residual limb volume due toweight-bearing pressures.

An amputee is a person who has lost part of an extremity or limb such asa leg or arm which commonly may be termed as a residual limb. Residuallimbs come in various sizes and shapes with respect to the stump. Thatis, most new amputations are either slightly bulbous or cylindrical inshape while older amputations that may have had a lot of atrophy aregenerally more conical in shape. Residual limbs may further becharacterized by their various individual problems or configurationsincluding the volume and shape of a stump and possible scar, skin graft,bony prominence, uneven limb volume, neuroma, pain, edema or soft tissueconfigurations.

Referring to FIGS. 1 and 2, a below the knee residual limb 10 is shownand described as a leg 12 having been severed below the knee terminatingin a stump 14. In this case, the residual limb 10 includes soft tissueas well as the femur 16, knee joint 18, and severed tibia 20 and fibula22. Along these bone structures surrounded by soft tissue are nervebundles and vascular routes which must be protected against externalpressure to avoid neuromas, numbness and discomfort as well as otherkinds of problems. A below the knee residual limb 10 has its stump 14generally characterized as being a more bony structure while an abovethe knee residual limb may be characterized as including more softtissue as well as the vascular routes and nerve bundles.

Referring to FIG. 2, amputees who have lost a part of their arm 26,which terminates in a stump 28 also may be characterized as havingvascular routes, nerve bundles as well as soft and bony tissues. Theresidual limb 10 includes the humerus bone 30 which extends from belowthe shoulder to the elbow from which the radius 34 and ulna 36 bones maypivotally extend to the point of severance. Along the humerus bone 30are the biceps muscle 38 and the triceps muscle 40 which still yet maybe connected to the radius 34 and the ulna, 36, respectively.

In some respects, the residual limb amputee that has a severed arm 26does not have the pressure bearing considerations for an artificial limbbut rather is concerned with having an artificial limb that isarticulable to offer functions typical of a full arm, such as bending atthe elbow and grasping capabilities. An individual who has a paralyzedlimb would also have similar considerations wherein he or she woulddesire the paralyzed limb to having some degree of mobility and thusfunctionality.

Historically, artificial limbs typically used by a leg amputee were forthe most part all made out of wood such as an Upland Willow. The limbswere hand carved with sockets for receiving the stump 14 of the residuallimb 10. Below the socket would be the shin portion with the foot belowthe shin. These wooden artificial limbs were covered with rawhide whichoften were painted. The sockets of most wood limbs were hollow as thelimbs were typically supported in the artificial limb by thecircumferential tissue adjacent the stump 14 rather than at the distalend of the stump 14.

Some artificial limbs in Europe were also made from forged pieces ofmetal that were hollow. Fiber artificial limbs were also used which werestretched around a mold after which they were permitted to dry and cure.Again, these artificial limbs were hollow and pretty much supported theresidual limb about the circumferential tissue adjacent the stump 14.

All of these various artificial limbs have sockets to put the amputee'sstump 14 thereinto. There are generally two categories of sockets. Thereare hard sockets wherein the stump goes right into the socket actuallytouching the socket wall without any type of liner or stump sock.Another category of sockets is a socket that utilizes a liner or insert.Both categories of sockets typically were opened ended sockets wherethey had a hollow chamber in the bottom and no portion of the sockettouched the distal end of the stump 14. So, the stump was supportedabout its circumferential sides as it fits against the inside wall ofthe sockets.

These types of sockets caused a lot of shear force on the stump 14 aswell as had pressure or restriction problems on the nerve bundles andvascular flow of fluid by way of the circumferential pressure effect ofthe socket on the limb. This pressure effect could cause a swelling intothe ends of the socket where an amputee may develop severe edema anddraining nodules at the end of their stump 14.

With time, prosthetists learned that by filling in the socket's hollowchamber and encouraging a more total contact with the stump and thesocket, the swelling and edema problems could be eliminated. However,the problematic tissue configurations, such as bony prominences,required special consideration such as the addition of soft or pliablematerials to be put into the socket.

Today, most artificial limbs are constructed from thermoset plasticssuch as polyester resins, acrylic resins, polypropylenes andpolyethylenes, which are perhaps laminated over a nylon stockinettewhich also may be impregnated by the various resins.

In the past, most artificial limbs were suspended from the amputee'sbody by some form of pulley, belt or strap suspension often used withvarious harnesses and perhaps leather lacers or lacings. Another methodof suspending artificial limbs is known as the wedge suspension whereinan actual wedge is built into the socket which is more closed at its topopening. The wedge in the socket cups the medial femoral condyle orknuckle at the abductor tubical. Yet another form of suspension isreferred to as the shuttle system or a mechanical hookup or linkupwherein a thin suction liner is donned over the stump that has a dockingdevice on the distal end which mechanically links up with itscooperative part in the bottom of the socket chamber. Sleeve suspensionswere also used wherein the amputee may use a latex rubber tube whichforms into a rubber-like sleeve which would be rolled on over both thetop of the artificial limb and onto the amputee's thigh. The sleevesuspensions have been used in combination with other forms ofsuspensions techniques.

Both the use of a positive pressure system and the use of a negativepressure system (or hypobaric closed chamber) have been utilized in thefield of prosthetics. At one time, for pressure systems “inflatableinner tubes” were used to fit into sockets. Presently, there arepneumatic “bags” which are strategically placed over what peopleconsider to be good weight-bearing areas to increase pressure to helpaccommodate for volume changes within the socket.

The problem with this is that it is a very specific pressure and createsatrophy and loss of tissue dramatically over these high pressure areas.None of these systems employs positive pressure distributed over thetotal contact area between the residual limb and the artificial limbsocket to accommodate volume changes within the socket.

The negative pressure aspects have been utilized for a closed chamber inthat a socket is donned by pulling in with a sock, pulling the sock outof the socket and then closing the opening with a valve. This creates aseal at the bottom and the stump is held into the socket by thehypobaric seal.

The older systems were initially started in Germany. They were anopen-ended socket, meaning there was an air chamber in the bottom of thesocket. This did not work particularly well because it would causeswelling of the residual limb into the chamber created by the negativedraw of suspending the weight of the leg and being under a confinedarea. This would lead to significance edema which would be severe enoughto cause stump breakdown and drainage.

It was later discovered in America that total contact was essentialbetween the residual limb and the socket and once you had total contactthe weight was distributed evenly or the suspension was distributed overthe whole surface of the limb rather than just over the open chamberportion of the socket.

The human body as a whole is under approximately one atmosphere ofpressure at sea level. It keeps and maintains a normal fluid systemthroughout the body. When an amputee dons a prosthesis and begins takingthe pressures of transmitting the weight of the body through the surfacearea of the residual limb to the bone, there is increased pressure onthe residual limb equal to one atmosphere plus whatever additionalpressures are created by weight bearing. This increased pressure causesthe eventual loss of fluids within the residual limb to the largerportion of the body which is under less pressure. This loss of fluidscauses the volume of the residual limb to decrease during the day. Itvaries from amputee to amputee, but it is a constant among all amputeeand the more “fleshy” and the softer the residual limb, the more volumefluctuation there will be. The greater the weight and the smaller thesurface area, the greater the pressures will be and the more “swings”there will be in fluids. In the past, the amputee had to compensate forthis volume decrease by removing the artificial limb and donningadditional stump socks to make up for the decreased residual limbvolume.

U.S. Pat. No. 5,888,230 discloses the use of a vacuum pump connectedbetween the limb and a liner. However, this invention is essentiallyinoperable because the liner will conform to the stump at all times, byan interference fit, so that there is no space between the residual limband the liner against which to draw a vacuum. In any case, the patentdoes not disclose application of vacuum to the socket cavity in such amanner as to draw the residual limb firmly and totally against theinterior of the socket. Instead, the patent discloses the use of shimsbetween the liner and the socket. Without total contact between theresidual limb and the socket, the limb may swell into the space betweenthe limb and the socket. Also, the patent does not disclose the use ofvacuum to prevent reduction in volume of the artificial limb due toweight- bearing pressures.

While some of these devices addressed some of the problems associatedwith prosthetics, none of the artificial limbs, liners and socket,individually or in combination, offered a prosthesis that presented atotal contact relationship with the residual limb; absorbed anddissipated shear, shock and mechanical forces transmitted to the limbtissues by the artificial limb; controlled residual limb volume; andused negative pressure as a locking device to hold the residual limbinto the socket.

There is a need for an improved hypobarically-controlled artificial limbthat will offer total contact relationship with the residual limb;absorb and dissipate shock, mechanical and shear forces typicallyassociated with ambulation, twisting and turning and weight bearing withan artificial limb; control residual limb volume by way of even weightdistribution; use negative pressure as a locking device to hold theresidual limb into the socket without causing swelling of the residuallimb into the socket; and control residual limb volume changes by anegative pressure system. Ideally, the vacuum system should beautomatically regulated.

U.S. Pat. No. 5,549,709 discloses several embodiments of ahypobarically-controlled artificial limb. However, all of theseembodiments required two sockets: an outer socket and an inner socket.Applicant has found that the present invention offers improvedperformance without the requirement for two sockets. A single socketworks equally well or better than two sockets. Also, this patent doesnot disclose a mechanism for maintaining vacuum in the presence of airleakage into the socket.

It has been found that it is essentially impossible to maintain aperfect, airtight seal between the residual limb and the socketsdisclosed in U.S. Pat. No. 5,549,709, with the result that slow airleakage into the sockets diminishes the vacuum in the sockets. With thereduction in vacuum, the beneficial effects of the vacuum also slowlydiminish. Consequently, there is a need for a means for maintaining thevacuum in the socket cavity in the presence of some air leakage past theseal.

SUMMARY OF THE INVENTION

A hypobarically-controlled artificial limb for amputees includes asingle socket with a volume and shape to receive a substantial portionof the residual limb. A sealed cavity is formed between the socket andthe residual limb. The wearer may use a liner over the residual limb forcomfort. A vacuum source is connected to a vacuum valve connected to thecavity to suspend the artificial limb from the residual limb and tocontrol and minimize volumetric and fluid changes within the residuallimb. To compensate for some air leakage past the seal, there is amechanism to maintain the vacuum in the cavity. A method for preventingthe loss of residual limb volume due to weight-bearing pressuresincludes the steps of: inserting the residual limb into a socket with acavity; making a seal between the residual limb and the socket; applyinga vacuum to the socket cavity to thereby draw the residual limb intofirm and total contact with the socket; maintaining the vacuum in thesocket cavity in the presence of some leakage past the seal; andopposing the loss of body fluids from the residual limb due toweight-bearing pressures, by means of the total contact relationship ofthe liner with the residual limb and the vacuum drawing the liner intofirm and total contact with the socket.

A principle object and advantage of the present invention is that ituses vacuum within the artificial limb socket to suspend the artificiallimb from the residual limb.

Another object and advantage of the present invention is that it usesvacuum within the artificial limb socket to assist in socket fit andminimizes volumetric limb changes within the socket.

Another object and advantage of the present invention is that it usesvacuum within the socket to lock the residual limb into the socket whilepreventing negative draw within the socket from causing swelling of theresidual limb into the socket.

Another object and advantage of the present invention is that it usesvacuum within the socket to oppose the loss of fluids from the residuallimb caused by weight-bearing pressures.

Another object and advantage of the present invention is that the vacuummay be created by a pump with a mechanical or motor drive.

Another principal object and advantage of the present invention is thatit may comprise only a single socket, rather than two sockets,simplifying construction and reducing cost and complexity.

Another principal object and advantage of the present invention is thatit includes a mechanism that can be used to maintain vacuum in thecavity between the residual limb or liner and the socket as air leaksinto the cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of the tissue and skeletal structureof an amputee's residual limb;

FIG. 2 is a side elevational view of a residual limb in the form of anamputated arm showing the skeletal and muscular structure of theresidual limb;

FIG. 3 is an exploded elevational view of the residual limb donning thepolyurethane sleeve, stretchable nylon sleeve, liner, nylon sheath andsocket of an artificial limb;

FIG. 4 is a cross-section of the artificial limb in FIG. 3, which is afirst embodiment of the artificial limb;

FIG. 5 is a cross-section of the artificial limb similar to FIG. 4,showing a second embodiment of the artificial limb;

FIG. 6 is the same as FIG. 5, but showing compression of the innersocket under the influence of positive air pressure;

FIG. 7 is a cross-section of the artificial limb showing a thirdembodiment of the artificial limb;

FIG. 8 is a cross-section of the artificial limb showing a fourthembodiment of the artificial limb;

FIG. 9 is an elevational view of the polyurethane sleeve and secondstretchable nylon sleeve rolled over the socket and residual limb withclothing shown in broken outline;

FIG. 10 is a cross-section of the artificial limb showing a fifthembodiment of the artificial limb;

FIG. 11 is a cross-section of the artificial limb showing a sixthembodiment of the artificial limb;

FIG. 12 is a detailed view of the vacuum mechanism in FIG. 11;

FIG. 13 is a cross-section of the artificial limb showing a seventhembodiment of the artificial limb;

FIG. 14 is a detailed view of the vacuum mechanism and suspension sleeveof FIG. 13;

FIG. 15 is a cross-section of the artificial limb showing an eighthembodiment of the artificial limb; and

FIG. 16 is a cross-section of the artificial limb showing a ninthembodiment of the artificial limb.

FIG. 17 is a cross section of the artificial limb showing a liner withan annular seal.

FIG. 18 is a cross-section of the artificial limb showing a secondembodiment of the liner of FIG. 17.

FIG. 19 is a partial cross-section of the artificial limb showing athird embodiment of the liner of FIG. 17.

FIG. 20 is a partial cross-section of the artifical limb showing afourth embodiment of the liner of FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The drawings show a number of different embodiments of an apparatus andmethod for managing the volume of a residual limb within an artificiallimb, by applying a vacuum source to the artificial limb cavity. It willbe seen that application of the vacuum to the cavity draws the residuallimb (which may be encased in a liner) firmly and totally against thesocket, thereby preventing swelling of the residual limb into thesocket, because there is no open chamber into which the residual limbmay be drawn by the vacuum. Importantly, application of the vacuum tothe cavity also opposes the loss of fluids from the residual limb due toweight-bearing pressures.

FIGS. 3 and 4 show one embodiment of the apparatus 50 of the presentinvention. The hypobarically-controlled artificial limb 50 includes anouter socket 52, shin 54, and foot 56. The outer socket 52 has a volumeand shape to receive a substantial portion of the residual limb 14 witha space 58 therebetween.

The apparatus 50 further includes a flexible inner socket 60 with acavity 62 with a volume and shape for receiving a substantial portion ofthe residual limb 14 and fitting in the space 58 between the outersocket 52 and the residual limb 14. The inner socket 60 has an innersurface 64 opposing the residual limb 14 and an outer surface 66opposing the outer socket 52.

A vacuum source 70 may conveniently be attached to the shin or pylon 54.The vacuum source 70 may preferably be a mechanical or motor-driven pump72. The vacuum source 70 may be connected to a power source 83, whichmay be a battery.

A vacuum valve 74 is suitably connected to the vacuum source 70. Thevacuum valve 74 may preferably be disposed on the outer socket 52. Avacuum tube 76 connects the vacuum valve 74 to the cavity 62. It will beseen that the vacuum source will cause the residual limb 14 to be drawninto firm contact with the inner surface 64 of the inner socket 60.

The hypobarically-controlled artificial limb 50 also includes aregulator means 80 for controlling the vacuum source 70. Preferably, theregulator means 80 may be a digital computer 82. Alternately, theregulator means may be a vacuum regulator. The regulator means 80 isconnected to a power source 83, which may be a battery.

A seal means 84 makes an airtight seal between the residual limb 14 andthe outer socket 52. Preferably, the seal means 84 is a nonfoamed,nonporous polyurethane suspension sleeve 86 which rolls over and coversthe outer socket 52 and a portion of the residual limb 14.Alternatively, the seal means 84 may be any type of seal which isairtight.

The hypobarically-controlled artificial limb 50 may also include a thinsheath 90 between the residual limb 14 and the inner surface 64 of theinner socket 60. As vacuum is applied to the cavity 62, the sheath 90will allow the vacuum to be evenly applied throughout the cavity 62.Without the sheath 90, the residual limb 14 might “tack up” against theinner surface 64 and form a seal which might prevent even application ofthe vacuum to the cavity 62. The sheath 90 may also be used to assistthe amputee into a smooth and easy fitting into the inner socket 60. Thesheath 90 is preferably made of thin knitted nylon.

The apparatus 50 may also include a nonfoamed, nonporous polyurethaneliner 92 receiving the residual limb 14 and disposed between the sheath90 and the residual limb 14. The liner 92 provides a total-contacthypobaric suction, equal weight distribution socket liner. The liner 92readily tacks up to the skin of the residual limb 14 and provides totalcontact with the limb 14. The liner 92 absorbs and dissipates shock,mechanical and shear forces typically associated with ambulation.

The hypobarically-controlled artificial limb 50 may also include astretchable nylon second sleeve 94 for rolling over and covering thesuspension sleeve 86 to prevent clothing from sticking to and catchingthe suspension sleeve 86.

Referring to FIG. 3, the polyurethane tubular sleeve 86 may beappreciated alone and in combination with the urethane liner 92 togetherwith the optional nylon sheath 90 and second stretchable nylon sleeve94.

More specifically, the amputee takes the stretchable nylon second sleeve94, suitably made of a spandex-like material and rolls it up over thestump 14 to the upper portions of the residual limb suitably as thethigh of a leg 12. Next, the polyurethane sleeve 86 is also rolledupwardly over the residual limb 10. Thereafter, the liner 92 isoptionally donned.

Next, the amputee may optionally utilize the nylon sheath 90 which issuitably of a non-stretching, thin, friction reducing nylon. As stated,this sheath 90 optionally may be used to assist the amputee into asmooth and easy fitting into the inner socket 60. Alternatively, thesheath 90 may be avoided and the liner 92 simply inserted into the innersocket 60 of the artificial limb 50.

Next, the amputee simply grasps the rolled over portion of thepolyurethane sleeve 86 and rolls it over a substantial portion of theouter socket 52. The sleeve 86 makes an airtight seal between theresidual limb 14 and the outer socket 52.

As can be appreciated, the polyurethane sleeve 86 is tacky.Consequently, the stretchable nylon second sleeve 94 may be utilized androlled over the polyurethane sleeve 86.

The amputee then sets the regulator means 80 to cause the vacuum source70 to apply vacuum through the vacuum valve 74 and vacuum tube 76 to thecavity 62. Enough vacuum is applied to cause the residual limb (withoptional coverings) to be drawn firmly against the inner surface 64 ofthe inner socket 60, which is flexible. The vacuum source 70 maypreferably maintain a vacuum in the range of 0 to 25 inches of mercury(ideally ten to twenty five inches).

It will be seen that the vacuum within the inner socket 60 will causethe hypobarically-controlled artificial limb 50 to be suspended from theresidual limb 14. The vacuum will lock the residual limb 14 into theinner socket 60 without causing swelling of the residual limb into thesocket, because of the total contact of the residual limb 14 with theinner socket 60. That is, there is no open chamber between the residuallimb 14 and the inner socket 60 which would draw on the residual limb.

As the volume of the residual limb 14 decreases during the day due toweight-bearing pressures, the regulator means 80 may appropriatelyadjust the vacuum source 70 to draw the residual limb 14 more firmlyagainst the inner socket 60 and thus compensate for the loss of residuallimb volume. The vacuum may also partially or completely oppose the lossof fluids from the residual limb caused by weight-bearing pressures.

A second embodiment of the apparatus 50 is shown in FIGS. 5 and 6. Thesecond embodiment of the apparatus 50 is as described above, with theexception that the inner socket 60A is compressible as well as beingflexible. Instead of a vacuum source, the second embodiment has apositive air pressure source 100, which may preferably be a motor-drivenpump 102. The regulator means 80, which may be a digital computer 82,controls the positive air pressure source 100. The regulator means andpositive air pressure source 100 are connected to a power source 83,which may be a battery. A positive pressure valve 104 connects the space58 to the positive air pressure source 100, for compressing the innersocket 60A as the volume of the residual limb decreases.

It will be seen that as the volume of the residual limb 14 decreasesduring the day due to weight-bearing pressures, the regulator means 80may control the positive air pressure source 100 to cause air pressureto compress the inner socket 60A to compensate for the decreased volumeof the residual limb, as shown in FIG. 6.

A third embodiment of the hypobarically-controlled artificial limb 50 isshown in FIG. 7. The third embodiment is a combination of the first andsecond embodiments described above.

The mechanical motor-driven pump 72 may act as both the vacuum source 70and the positive air pressure source 100. The regulator means 80, vacuumsource 70 and positive air pressure source 100 are connected to a powersource (not shown), which may be a battery.

The vacuum source 70, under control of the regulator means 80, willcompensate for reduced residual limb volume up to a certain point. Fromthat point on, the regulator means 80 will cause the positive airpressure source 100 to further compensate for reduced residual limbvolume as described above. The third embodiment thus uses both vacuumand positive air pressure working together to lock the residual limb 14into the inner socket 60 and reduce socket volume to compensate forfluid loss in the residual limb 14. The exact point at which thechangeover is made between vacuum compensation and positive air pressurecompensation is controlled by the regulator means 80, which as describedmay be a digital computer appropriately programmed for the socketenvironment.

A fourth embodiment of the apparatus 50 is shown in FIG. 8. The fourthembodiment is like the first embodiment, but includes two vacuum valves:a first vacuum valve 106 and a second vacuum valve 110, both connectedto the vacuum source 70. The first vacuum valve 106 connects the vacuumsource 70 to the space 58. The space 58 contains a semi-compressiblematerial 108, such as polystyrene beads, as disclosed in U.S. Pat. No.4,828,325, herein incorporated by reference.

To don the artificial limb 50, the amputee proceeds as described above.After inserting the residual limb 14 (with optional coverings) into theinner socket 60B, which is both compressible and expandable, and rollingthe suspension sleeve 86 over the outer socket 52, the amputee activatesthe regulator means 80, causing the vacuum source 70 to apply a vacuumto the space 58. This causes the material 108 to lock mechanicallytogether into a rigid mass, conforming to the shape of the residual limb14. The inner socket 60B may expand slightly under the weight of theresidual limb 14 and under the influence of vacuum.

It will be seen that the semi-compressible molding material 108 can bemolded to the contours of the residual limb 14 without using acustom-building process to produce a custom socket. The outer socket 52may appropriately occur in standard sizes, such as small, medium, andlarge. The inner socket 60B may also occur in standard sizes such assmall, medium, and large. Adaptation of the inner socket 60B to thecontours of the residual limb 14 occurs through solidifying the material108 under the influence of vacuum.

The second vacuum valve 110 connects the vacuum source 70 to the cavity62 as previously described, for locking the residual limb 14 into theinner socket 60B.

The fourth embodiment may also include a positive air pressure source100 as previously described, to adjust the size of the inner socket 60Bto compensate for decreased residual limb volume.

The fourth embodiment may also include a thin sheath 90, liner 92, andsecond sleeve 94, as previously described.

The positive air pressure source 100 may also be used for shockabsorption and a dynamic response in the ankle and foot sections of theartificial limb 50, by means of a connection 120.

A fifth embodiment of the hypobarically-controlled artificial limb 50 isshown in FIG. 10. This embodiment is the same as the first embodimentshown in FIG. 4, with some changes. First, vacuum source 71 may be ahand-operated vacuum pump 71 which may remove air from the cavity 62down to approximately 10-25 inches of mercury. A suitable hand-operatedvacuum pump is marketed under the trademark MITY VAC II® by NewardEnterprises, Inc. of Cucamonga, Calif.

The fifth embodiment also includes the seal means 84 which preferablyconsists of a non-foamed, nonporous polyurethane suspension sleeve 86for rolling over and covering a portion of the residual limb 14. Aportion of the seal means 86 is adapted to be disposed between the outersocket 52 and the inner socket 60. The sleeve may be made of any of avariety of air-impervious elastomers.

The fifth embodiment, shown in FIG. 10 also includes a mechanicalinterlock 67, 59 for interlocking the inner socket 62 with the outersocket 52. Preferably, the mechanical interlock consists of a firstdetent 67 in the inner socket 62 and a second detent 59 in the outersocket 52. The first detent 67 engages the second detent 59 to lock theinner socket 60 into the outer socket 52.

A sixth embodiment of the apparatus of the present invention is shown inFIGS. 11 and 12. The sixth embodiment is like the first embodiment shownin FIG. 4, with some changes.

First, the inner socket is specifically intended to be removably fromthe outer socket. To provide a positive mechanical connection betweenthe inner socket and outer socket and yet allow the inner socket to beeasily removed, the sixth embodiment includes a mechanical interlock 103engaging the inner socket 60 and the outer socket 52. Preferably, themechanical interlock may be an extension 104 which is attached to theinner socket 60 and a docking device 106 attached to the outer socket 52and receiving the extension 104, and a locking mechanism 105 engagingthe extension 104 and the docking device 106.

The extension may be any sort of protrusion from the inner socket, suchas a bulge or tab. Preferably, the extension 104 comprises a shuttle pin108.

The locking mechanism may be any sort of member which engages both theextension 104 and the docking device 106, such as a screw, wire, or pin.Preferably, the locking mechanism 105 comprises a second pin 110 whichextends outside the outer socket 52 as to be accessible.

Second, the sixth embodiment includes two thin sheaths, rather than one.A first inner sheath 90 may preferably be disposed between the residuallimb 14 and the inner surface 64 of the inner socket 60. As vacuum isapplied to the cavity 62, the inner sheath 90 will allow the vacuum tobe evenly applied throughout the cavity 62. Without the inner sheath 90,the residual limb 14 might “tack up” against the inner surface 64 andform a seal which might prevent even application of the vacuum to thecavity 62. The inner sheath 90 may also be used to assist the amputeeinto a smooth and easy fitting into the inner socket 60.

An outer sheath 93 is preferably disposed between the suspension sleeve86 and the inner socket 60, thereby preventing the suspension sleevefrom tacking to the inner socket 60. Such tacking would cause frictionbetween the inner socket 60 and the sleeve 86 which would cause thesleeve to wear out. Such tacking might also cause restrictions in themovement of the residual limb. The outer sheath 93 also protects thesuspension sleeve 86 from being damaged by friction with the innersocket 60.

The sixth embodiment also preferably includes an adhesive pressure tape95 adapted to cover the outer sheath 93, suspension sleeve 86, and thesecond sleeve 94 and sealing the outer sheath 93, suspension sleeve 86,and the second sleeve 94 to the inner socket 60. The tape 95 locks allof these layers to the inner socket so that they do not come looseduring movement.

In the sixth embodiment, the suspension sleeve 86 goes between the innersocket 60 and the outer socket 52, so that the sleeve 86 is protectedfrom damage.

In the sixth embodiment, the inner socket 60 has a rigid lower portion98 and a substantially flexible upper portion 96. The rigid lowerportion assists in weight-bearing while the substantially flexible upperportion allows for movement of the residual limb 14. As the knee is bentfrom fully straight to fully flexed, the width of the knee changesrather significantly and in a hard, non-flexible socket brim, there canbe excessive pressure on the residual limb 14. The substantiallyflexible upper portion 96 makes the artificial limb 50 more comfortableand more adaptive to these changes. For the same reason, the outersocket 52 has a rigid lower portion 102 and a substantially flexibleupper portion 100.

Preferably, the top edge of the inner socket 60 is below the top edge ofthe outer socket 52 so that the sleeve 86 is protected from impact.Preferably, the top edge of the inner socket 60 may be {fraction (3/16)}inch below the top edge of the outer socket 52.

The sixth embodiment includes extensive modifications to the vacuumsystem.

First, a vacuum fitting 78 has been added to the inner socket 60 toattach the vacuum tube 76. The vacuum fitting 78 allows the attachmentof a vacuum sensor 79 adapted to sense the amount of vacuum in thecavity 62 and a sensor lead 81 is attached to the sensor 79 connectingthe sensor 79 to the regulator means 80, thus conveying the sensedvacuum to the regulator means 80.

A vacuum valve 74 is placed between the cavity 62 and the vacuum source70 to maintain vacuum in the cavity 62. Typically, the vacuum valve 74is a one-way valve or non-return valve.

In the sixth embodiment, the vacuum source 70, vacuum tube 76, vacuumvalve 74, regulator means 80, and power source 83 are all attached tothe outer socket 52 in the space 58 between the outer socket 52 andinner socket 60. In this way, these delicate components are protectedagainst being damaged by impact. Because of the placement of theregulator means 80 within the outer socket 52, a vacuum control 77 isprovided extending outside the outer socket 52 to allow manual controlof the regulator means 80.

The amputee dons the sixth embodiment in a manner similar to thatearlier described, with some modifications. First, the outer sheath 93is put on the residual limb 14 after rolling the suspension sleeve 86upward over the residual limb and before donning the liner 92. Afterdonning the inner sheath 90 over the liner 92, the amputee inserts theresidual limb 14 into the inner socket 60. Next, the outer sheath 93,suspension sleeve 86, and second sleeve 94 are rolled down over theinner socket 60, and the adhesive pressure tape 95 is applied. Next, thewearer sets the regulator means 80 to an appropriate vacuum level bymeans of the vacuum control 77, and connects the vacuum tube 76 to thevacuum fitting 78. The inner socket 60 is then placed within the outersocket 52 so that the shuttle pin 108 engages the docking device 106 andthe locking pin 110 is set to engage the shuttle pin 108 and the dockingdevice 106, providing a positive mechanical interlock.

A seventh embodiment of the hypobarically-controlled artificial limb ofthe present invention is shown in FIG. 13. The seventh embodiment issimilar to the sixth embodiment, with some changes.

First, the mechanical interlock 103 does not engage the inner socket 60.Instead, the mechanical interlock engages the outer socket 52 and thesuspension sleeve 86. To accomplish this, the suspension sleeve 86covers the entire inner socket 60, and the suspension sleeve 86 has theextension 104 or shuttle pin 108 embedded in the suspension sleeve atthe distal end of the suspension sleeve, as shown in FIG. 14.Preferably, the extension 104 has a portion 104A embedded in thesuspension sleeve. This portion 104A may be a disk or umbrella 104A. Theextension 104 then engages the docking device 106 as previouslydescribed.

Second, the suspension sleeve 86 is modified to support the additionalweight imposed on the suspension sleeve 86 due to the outer socket 52and artificial limb. In particular, the suspension sleeve 86 isfabricated from a material which allows circumferential expansion butresists longitudinal stretching under the weight of the artificial limb.Such a material is described in U.S. Pat. No. 5,571,208, hereinincorporated by reference.

The sleeve 86 preferably contains fabric threads which may be orientedcircumferentially around the sleeve. The threads preferably arecomprised of double-knit polyurethane. The threads may also includenylon. The threads permit the sleeve 86 to expand circumferentially sothat the sleeve may be slipped onto the residual limb 14 and so that thelower portion may be slipped over the inner socket 52. The threads arepreferably connected together with cross-links, which also may bepreferably comprised of polyurethane. The cross-links and threads form amatrix which allows circumferential expansion but resists longitudinalstretching under the weight of the artificial limb. By example, thesleeve 86 may have a 4-to-1 ratio of circumferential stretch relative tolongitudinal stretch.

The sleeve 86 may have a portion above the inner socket 52 which ismanufactured of material which allows both vertical and horizontalstretching, to increase flexibility.

An eighth embodiment of the hypobarically-controlled artificial limb ofthe present invention is shown in FIG. 15.

Unlike earlier embodiments, the artificial limb 50 of the eighthembodiment has only a single socket 60 rather than inner and outersockets and is thus considerably simpler.

The socket 60 has a volume and shape to receive a substantial portion ofthe residual limb 14 with a cavity 62 therebetween.

A nonfoamed, nonporous polyurethane liner 92 is preferably adapted toreceive the residual limb 14 and to be disposed between the residuallimb 14 and the socket 60.

A vacuum source 70 is connected to the cavity 62 by a vacuum valve 78,thereby drawing the residual limb 14 into firm contact with the socket60.

A seal means 84 makes a seal between the residual limb 14 and the socket60 to minimize air leakage into the cavity 62. It has been found that itis impossible to make a perfect seal, with the result that air leakagecan occur at rates up to 30 cc per minute. As air leaks into the cavity62, it is necessary to activate the vacuum source 70 to restore vacuumin the cavity. Furthermore, it has been found that when the vacuum inthe cavity is about 5 inches of mercury, the residual limb may lose upto 6 to 15% of its volume during the day, whereas if the vacuum in thecavity is 10-25 inches of mercury, the residual limb loses only about 1%of its volume during the day.

To minimize the time that the vacuum source, such as a vacuum pump 72,needs to run to maintain vacuum in the cavity, a ninth embodiment of theartificial limb 50 is shown in FIG. 16. The ninth embodiment is the sameas the eighth embodiment, but a vacuum reservoir 110 is added betweenthe vacuum source 70 and the vacuum valve 78. The vacuum reservoir 110has a volume substantially larger than the cavity 62. Suitably, thevacuum reservoir may have a volume of 2 gallons or 9000 cc while thevolume of the cavity 62 may be only about 100 cc or even less.

It will be seen that as air leaks into the cavity 62, the air will bepulled into the vacuum reservoir 110, thereby maintaining the vacuum inthe cavity 62.

When the vacuum in the reservoir 110 reaches a certain minimumthreshold, the vacuum source 70 may be activated to restore vacuum tothe vacuum reservoir 110. The vacuum source 70 may be activated eithermanually or by a regulator means (not shown).

The artificial limb 50 typically includes a shin or pylon 54 and a foot56, as shown in FIG. 3. Preferably, the vacuum reservoir 110 is attachedto the shin 54 between the socket 60 and the foot 56. However, thevacuum reservoir may also be carried separately, as for example in abackpack. Depending on the placement of the vacuum reservoir 110, avacuum tube 76 may be necessary to connect the vacuum reservoir 110 tothe vacuum valve 78.

If the volume of the vacuum reservoir 110 is about 9000 cc and air leaksinto the cavity 62 at about 75 cc per minute, it will be seen that theintervals between activation of the vacuum source 70 can be up to about120 minutes.

The artificial limb 50 of the eighth and ninth embodiments maypreferably further comprise the following.

An inner sheath 90 may be adapted to be disposed between the liner 92and the socket, to ensure even distribution of vacuum in the cavity 62,as earlier described. Preferably, the inner sheath 90 may be thinknitted nylon. The sheath 90 may also be affixed to the outside of theliner 92.

The seal means 84 is preferably a nonfoamed, nonporous polyurethanesuspension sleeve 86 for rolling over and covering the socket 60 and aportion of the artificial limb 14, as earlier described.

A stretchable nylon second sleeve 94 for rolling over and covering thesuspension sleeve 86 may be added to prevent clothing from sticking toand catching on the suspension sleeve 86, as earlier described.

The vacuum source 70 is preferably a motor or mechanical driven vacuumpump 72, as earlier described. A vacuum tube 76 may be necessary toconnect the vacuum pump 72 to the vacuum valve 78, depending on theplacement of the vacuum pump 72.

The vacuum source 70 may also be a weight-actuated vacuum pump and shockabsorber as disclosed in U.S. Patent application Ser. No. 09/534,274,filed Mar. 23, 2000 and herein incorporated by reference.

To maintain the vacuum in the cavity, either a regulator means 80, avacuum reservoir 110, or a weight-actuated vacuum pump and shockabsorber as disclosed in U.S. patent application Ser. No. 09/534,274,may be employed.

Applicant has found that many of the embodiments discussed earlier sharea common problem. The vacuum which holds the residual limb (and liner)in firm contact with the socket tends to cause edema and blistering atthe point on the residual limb where the suspension sleeve contacts theresidual limb. This problem occurs because the vacuum (perhaps 7½ poundsof negative pressure) in cavity 62 draws against the suspension sleeve86 at the point where the suspension sleeve 86 contacts the skin of theresidual limb. However, because the liner 92 often has an outer fabriccover 130 to prevent the liner from adhering to the socket 60 orclothing, the suspension sleeve cannot make a good seal at the pointwhere it contacts the outer fabric cover 120. This has left the residuallimb as the only point at which to make the seal.

FIG. 17 shows one solution to this problem. The liner 92 is improved byadding an annular seal 140 extending outwardly from the fabric cover130. The annular seal, which may be made from the same material as theinner layer 92 of the liner, is adapted to sealingly engage thesuspension sleeve 86, producing a seal against the vacuum in cavity 62at the point of contact with the suspension sleeve 86. Therefore, thevacuum in cavity 62 now draws against the annular seal 130 rather thanagainst the skin of the residual limb 14.

An alternative solution to the above problem is shown in FIG. 18. Here,the annular seal 140 does not make contact with the suspension sleeve86, but rather makes contact with the inner wall 63 of the socket 60,and makes a seal at that point. No suspension sleeve is used in thisvariation, it being found that sufficient holding force is provided bythe vacuum in cavity 62.

A second alternative is shown in FIG. 19. This alternative is like thatof FIG. 18, with the exception that a mechanical interlock 103 isprovided which is adapted to interlock with the socket 60. Preferably,as shown, the mechanical interlock 103 comprises a shuttle pin 108adapted to connect the liner 92 with the socket 60, and a lockingmechanism 105 such as a second pin 110 extending through the socket 60to the exterior of the socket 60 for access by the amputee as earlierdescribed. More particularly, the liner 92 may have an extension 104 orshuttle pin 108 embedded in the liner at the distal end of the liner.Preferably, the extension 104 has a portion 104A which may be a disk orumbrella which engages a docking device 106 as earlier described.

To keep air from entering the cavity 62, the invention of FIG. 19 alsopreferably includes a locking mechanism seal 150 adapted to engage theinner wall 63 of the socket 60 about the locking mechanism 105. The seal150 could alternatively be on the outer surface of the socket 60.

Another alternative is shown in FIG. 20. Here, the fabric cover 130stops below the annular seal 140. The annular seal 140 may also be madeof the same material as the liner 92.

A very important advantage, in all of the above embodiments, is the useof vacuum within the socket to prevent fluids from migrating out of thedistal end of the residual limb due to weight-bearing pressures.Although the exact mechanism is not precisely known at this time,Applicant believes this limb vacuum volume management system to functionas follows.

Application of a vacuum to the socket cavity 62 sucks the liner 92tightly against the inner wall of the socket 60. The liner has a tightinterference fit with the residual limb 14, so that the residual limb isalso butted tightly up against the inner wall of the socket. During theweight-bearing phase of walking, the wearer's body weight will force thelimb and liner even more tightly against the inner wall of the socket.However, during the non-weight-bearing phase, or swing phase, ofwalking, the weight of the artificial limb will have a tendency to causethe socket 60 to pull away from the liner 92. This is prevented by thevacuum in the socket cavity. Because the vacuum keeps the liner tightlyopposed to the inner wall of the socket, this tendency will also causethe liner 92 to pull away from the residual limb, creating a small,partial vacuum between the liner 92 and the residual limb 14. Thissmall, partial vacuum, perhaps on the order of 2 inches of mercury, willthen oppose the migration of fluids out of the residual limb.

In order for this beneficial effect of vacuum to occur, the vacuum inthe socket cavity 62 needs to be at least about 10 to 25 inches ofmercury. At this level of vacuum, it has been found that the residuallimb loses only about 1% of its volume during the day.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof, and it istherefore desired that the present embodiment be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than to the foregoing description to indicatethe scope of the invention.

What is claimed:
 1. In an artificial limb for amputees who have aresidual limb, an apparatus for managing residual limb volume, whereinapplication of a vacuum prevents loss of residual limb volume due toweight-bearing pressures and locks the residual limb to the artificiallimb without causing swelling of the residual limb, the apparatuscomprising: (a) a flexible liner having a cavity with a volume less thanthat of the residual limb, whereby the liner is tensioned into a totalcontact relationship with the residual limb; (b) a single socket with avolume and shape to receive a substantial portion of the residual limband the liner, the socket having a cavity adapted to receive theresidual limb and the liner; (c) a vacuum source connected to the socketcavity between the liner and the socket, wherein application of thevacuum source to the socket cavity draws the residual limb and linerinto firm and total contact with the socket, thereby locking theresidual limb to the socket without causing swelling of the residuallimb into the socket; (d) a seal means for sealing the socket cavity;(e) a means to maintain a vacuum in the socket cavity, in the presenceof some air leakage past the seal means; and (f) further comprising athin sheath between the liner and the socket, to assist the evendistribution of vacuum in the cavity about the liner; whereinapplication of the vacuum source of the socket cavity prevents the lossof residual limb volume due to weight-bearing pressures.
 2. Theapparatus of claim 1, wherein a vacuum of at least ten inches of mercuryis maintained in the cavity.
 3. The apparatus of claim 1, wherein thesocket has a single wall.
 4. The apparatus of claim 1, wherein the sealmeans further comprises a nonfoamed, nonporous polyurethane suspensionsleeve for rolling over and covering the socket and a portion of theresidual limb.
 5. The apparatus of claim 1, wherein the liner is of anonfoamed, nonporous polyurethane.
 6. The apparatus of claim 1, whereinthe seal means further comprises an annular seal between the liner andthe socket.
 7. The apparatus of claim 1, wherein the vacuum source is avacuum pump and the means to maintain the vacuum in the cavity is aregulator, and further comprising a power source for the vacuum pump andthe regulator.
 8. The apparatus of claim 1, wherein the means tomaintain the vacuum in the cavity further comprises a vacuum reservoirhaving a volume substantially larger than the cavity.
 9. The apparatusof claim 1, wherein the vacuum source and the means to maintain thevacuum in the cavity further comprise a weight-actuated vacuum pump. 10.In an artificial limb for amputees who have a residual limb, anapparatus for managing residual limb volume, the artificial limb havinga socket, the socket having a cavity for insertion of the residual limb,wherein application of a vacuum to the cavity prevents loss of residuallimb volume due to weight-bearing pressures and locks the residual limbto the socket without causing swelling of the residual limb into thesocket, the apparatus comprising: (a) a flexible liner having a cavitywith a volume less than that of the residual limb, whereby the liner istensioned into a total contact relationship with the residual limb; (b)a single socket with a single wall and with a volume and shape toreceive a substantial portion of the residual limb and the liner, thesocket having a cavity adapted to receive the residual limb and theliner; (c) a vacuum source connected to the socket cavity between theliner and the socket, wherein application of the vacuum source to thesocket cavity draws the residual limb and liner into firm and totalcontact with the socket, thereby locking the residual limb to the socketwithout causing swelling of the residual limb into the socket; and (d) aseal means for sealing the socket cavity; wherein application of thevacuum source to the cavity also limits the loss of residual limb volumedue to weight-bearing pressures to about 1%.
 11. The apparatus of claim10, further comprising a means to maintain vacuum in the cavity in thepresence of some air leakage past the seal means.
 12. The apparatus ofclaim 11, wherein a vacuum of at least ten inches of mercury ismaintained in the cavity.
 13. The apparatus of claim 11, wherein thevacuum source is a vacuum pump and the means to maintain the vacuum inthe cavity is a regulator, and further comprising a power source for thevacuum pump and the regulator.
 14. The apparatus of claim 11, whereinthe means to maintain the vacuum in the cavity further comprises avacuum reservoir having a volume substantially larger than the cavity.15. The apparatus of claim 11, wherein the vacuum source and the meansto maintain the vacuum in the cavity further comprise weight-actuatedvacuum pump.
 16. The apparatus of claim 10, wherein the seal meansfurther comprises a nonfoamed, nonporous polyurethane suspension sleevefor rolling over and covering the socket and a portion of the residuallimb.
 17. The apparatus of claim 10, wherein the liner is of anonfoamed, nonporous polyurethane.
 18. The apparatus of claim 10,wherein the seal means further comprises an annular seal between theliner and the socket.
 19. The apparatus of claim 10, further comprisinga thin sheath between the liner and the socket, to assist the evendistribution of vacuum in the cavity about the liner.
 20. A method forpreventing the loss of residual limb volume due to weight-bearingpressures in an artificial limb, comprising the steps of: (a) insertingthe residual limb into a flexible liner with a volume less than that ofthe residual limb, whereby the liner is tensioned into a total contactrelationship with the residual limb; (b) inserting the residual limb andliner into a single socket having a volume and shape to receive theresidual limb and the liner, the socket having a cavity into which theresidual limb and liner are inserted; (c) sealing the socket cavity; (d)applying a vacuum to the socket cavity between the liner and the socket,thereby drawing the residual limb and liner into firm and total contactwith the socket; (e) maintaining a vacuum in the socket cavity to atleast ten inches of mercury below ambient, in the presence of some airleakage into the socket cavity; and (f) opposing the loss of body fluidsfrom the residual limb due to weight-bearing pressures, by means of thetotal contact relationship of the liner with the residual limb and thevacuum drawing the liner into firm and total contact with the socket.21. The method of claim 20, wherein the liner is of a non-foamed,non-porous polyurethane.
 22. The method of claim 20, wherein the sockethas a single wall.
 23. The method of claim 20, further comprising thestep of encasing the residual limb and the liner in a thin sheath toassist in the even distribution of vacuum about the liner.